Abrasive wheels



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4 TOP/v5) United States Patent ABRASIVE WHEELS Michael C. Klug, St. Paul, Minn. Application April 7, 1954, Serial No. 421,527

6 Claims. (Cl. 51--193.5)

This invention relates to abrasive wheels of the type having a hub adapted to be fastened to a power-driven shaft and flexible arms projecting from the hub in spaced relation one to another around the periphery thereof and each carrying on its leading face a strip of flexible abrasive material forming a segment of the abrasive peripheral surface to be applied to the work.

The principal object of my invention is to provide for an abrasive wheel of the class described improved means for detachably fastening the strips of flexible abrasive material in operative relation to the several supporting arms whereby the useful life of each such strip is prolonged and replacement of the strips is facilitated when they become worn or when strips carrying grits of a different grade are required.

A particular object is to provide in an abrasive wheel of the class described clamping means including compressible elastic hub segments which are operative to grip portions of the several abrasive strips whereby the strips are detachably held inplace in such manner as to minimize breakage or damage to them when they and their supporting arms are repeatedly bent backward and then sprung forward in the course of their normal operation.

The invention also includes certain other novel features of the strip clamping means which will be more fully pointed out in the following specification and claims.

Referring to the accompanying drawing which illustrates, by way of example and not for the purpose of limitation, two suitable forms of my invention:

Figure 1 is an end elevational view of one form of the invention, with portions of a hub clamping member broken away to show parts otherwise concealed;

Fig. 2 is a part side elevational view and part vertical sectional view showing the same form of the invention;

Fig. 3 is a part end elevational view and part sectional view showing another form of the invention, and

Fig. 4 is a part side elevational view and part sectional 1 view of the form of the invention shown in Fig. 3.

Referring to Figs. 1 and 2, the wheel is shown mounted on an axially disposed shaft 5. Fitting on this shaft is a hub portion 6 formed from a suitable compressible, elastic material, for example, natural or synthetic rubber of approximately 40 plastometer composition. Projecting outward from the hub portion 6 is a plurality of spaced arms 7 which are preferably integral with the hub 6 and constructed from similar flexible elastic material. The leading face of each of the arms 7 carries a strip 8 of flexible abrasive material having a coating 9 of granular abrasives. Extending in continuation of the leading face of each of the arms 7 is a recess 10 formed in the core 6 to receive the inner end portion of one of the abrasive strips 8.

Suitable clamping means for compressing the several segments of the hub 6 and thereby causing them to grip the several strips 8 in the recesses 10 may comprise a circular jaw member 11 fixed on the shaft and a similar but relatively movable jaw member 12 having a central opening which fits loosely on the shaft 5. Clamping force may be applied by means of a nut 13 which fits on a threaded portion 5a of the shaft and is operative to force the member 12 into clamping engagement with the hub 6. Fingers 11a are formed on the member 11 to confine the periphery of the hub 6 between the several arms 7 and similar fingers 12a are formed on the member 12 to engage the periphery of the hub. The compressive effect of the jaw members 11 and 12 is improved by forming substantially conical surfaces 14 on the fingers 11a and similar surfaces 15 on the fingers 12a so that the hub 6 is compressed radially inward when the nut 13 is tightened on the shaft.

By backing the nut 13 away from the member 12, pressure on the hub 6 may be relieved. This allows the hub surfaces defining the recesses 10 to recede from the abrasive strips and release them so that they may be with drawn from the hub recesses and replaced by new strips or by others carrying a different grade of abrasive grits. No other fastening is required for the abrasive strips because it is desirable to allow for limited relative movement of these strips and the supporting faces of the arms 7. With the strips in place on the leading faces of the arms 7, the nut 13 is merely tightened on the shaft 5 to force the clamp member 12 toward the member 11 and thereby compress the hub 6 sufiiciently to cause the inner end portions of the several abrasive strips to be gripped between the yielding surfaces of the hub segments in the recesses 10. During the operation of abrasive wheels of this character, each of the arms 7 is normally extended by centrifugal force as well as by the form of the arms and each arm and the abrasive strip carried thereby is bent backward as indicated in broken lines in Figs. 1 and 3 upon making contact with the work and assumes various positions, depending upon the pressure applied to the work. As each strip passes out of contact with the work it springs outward to the fully extended position shown in full lines. Thus during the working operation, the arms 7 and abrasive strips 8 carried thereby are constantly flexed and this has the beneficial effect of freeing the cuttings from the abrasive strips and minimizing the tendency of some kinds of cuttings to lodge between the abrasive grits. It will be evident that in the form of my invention shown in Figs. 1 and 2, the shaft 5 is adapted to be held in a chuck carried by either a hand operated or motor driven arbor and is particularly adapted to be fastened in the chuck of a motor driven portable drill chuck.

The form of the invention shown in Figs. 3 and 4 is embodied in an abrasive wheel of larger size. It has an inner hub portion 16 adapted to receive and be secured to a motor driven arbor. Integral with the hub portion 16 and spaced outward therefrom is a cylindrical hub portion 17 upon which is secured a series of hub segments 13 constructed from a compressible elastic material like that forming the hub 6. Integral with each of the segments 18 is a flexible arm 19 carrying on its leading face one of the strips 8 of abrasive material. The several segments 18, when not under compression, are spaced apart one from another at their surfaces 20 which extend in continuation of the leading faces of the several arms 19 so that there is a recess into which an inner end portion of each of the strips 8 may be inserted be tween the end surfaces of the segments 18.

To fasten each of the segments 18 in place and to apply compressive force thereto, I provide an arcuate clamping member 21 and a coacting clamp screw 22 for each segment 18. Each screw engages one of the members 21 in a countersunk socket 23 formed therein and is threaded in a suitably tapped hole in the hub member 17.

The operation of the form of the invention shown in Figs. 3 and 4 is similar to that hereinbefore described. The wheel hub 16 is merely secured to a suitable powerdriven arbor and, with the wheel rotating in the appropriate direction, the work is brought into contact with the surfaces 9 of the abrasive strips carried by the arms 19. The several arms 19 and the abrasive strips carried thereby are bent backward and then released intermittently and successively so that during the operation highly eflicient abrasive cutting action is obtained. When one or more of the strips 8 becomes worn they may be replaced by new strips having grits of the same or a difierent grade or size.

The replacement of any strip may be accomplished quickly and easily merely by suitable manipulation of the appropriate clamping screw or screws 22. Each screw, when loosened, frees the portion of the strip in engagement with the end surfaces 20 of the adjoining segments 18. Since these surfaces, like the corresponding surfaces of the hub 6 defining the recesses 10, are formed on compressible, relatively soft material there is no tendency to cut or break the abrasive strips when they strike the work or as they are alternately bent backward variously under the pressure of the work against their abrasive surfaces and then sprung to their extended positions. Consequently, it has been found that the useful life of the abrasive strips is prolonged and there is considerable saving in the work and time involved in changing the abrasive material when necessary.

I claim:

1. An abrasive wheel having flexible arms projecting from the periphery thereof in spaced relation one to another and flexible abrasive strips overlying the leading faces of said arms, the improvements which comprise, compressible elastic hub segments of the wheel formed to engage opposite sides of the inner end portions of the several abrasive strips and clamping means disposed to compress adjacent hub segments in gripping engagement with opposite sides of said end portions of the several abrasive strips.

2. An abrasive wheel in accordance with claim 1 wherein said clamping means comprise relatively movable jaw members overlying opposite surfaces of said compressible segments and threaded means engaging said relatively movable members and operative to hold said segments under compression.

3. An abrasive wheel having a substantially cylindrical hub, flexible arms projecting from the periphery of the substantially in continuation of the leading faces of the several arms to receive the inner end portions of the several abrasive strips between said gripping surfaces and clamping means disposed to compress said adjoining hub segments in gripping engagement with the inner end portions of the several abrasive strips.

4. An abrasive wheel in accordance with claim 3 wherein said clamping means comprise arcuate members engaging the peripheral surfaces of said hub segments and screw threaded means engaging the several arcuate members to confine and compress said segments on the cylindrical hub.

5. An abrasive wheel having an axially disposed supporting shaft, flexible arms projecting from the periphery of the wheel in spaced relation one to another and flexible abrasive strips adapted to overlie the leading faces of said arms, the improvements which comprise, compressible elastic hub segments formed with coacting normally substantially parallel surfaces adjacent to the leading faces of the several arms to engage opposite sides of the inner end portions of the several abrasive strips and clamping means operative to compress said hub segments in gripping engagement with the inner end portions of the several abrasive strips.

6. An abrasive Wheel in accordance with claim 3 wherein said clamping means comprise relatively movable jaw members engaging opposite surfaces of said hub segments and a nut having a threaded connection with said shaft whereby one of said jaw members may be forcibly actuated toward the other jaw member to compress the several hub segments between the jaw members.

References Cited in the file of this patent UNITED STATES PATENTS 1,670,068 Grimes May 15, 1928 2,316,257 Krastin Apr. 13, 1943 2,445,492 Pentecost July 20, 1948 2,535,637 Johnson Dec. 26, 1950 

